Langue d'oil vs Langue d'oil French

Langue d'oil and Langue d'oil French both are nouns.

Word	Noun	Adjective	Verb	Adverb
Langue d'oil	Yes	No	No	No
Langue d'oil French	Yes	No	No	No

As nouns, Langue d'oil and Langue d'oil French are synonyms defined as:

Langue d'oil and Langue d'oil French: medieval provincial dialects of French spoken in central and northern France

Langue d'oil (noun)	Langue d'oil French (noun)
medieval provincial dialects of French spoken in central and northern France	medieval provincial dialects of French spoken in central and northern France